VOL. v.] PHILOSOPHICAL TRANSACTIONS. 501 



expansion of the air he was then in, they left him early enough. And when 

 the internal receiver was taken out, he did not only recover from his fainting fit 

 sooner than before, but escaped those subsequent tremblings we have men- 

 tioned. 



Exp. IV. — Encouraged by this success, after we had allowed him some time to 

 recollect his strength, we reconveyed him and the odd vessel wherein he was 

 included into the former receiver, and pumped out the air till the mercury in 

 the gauge was not only drawn down as low as formerly, but nearly half an 

 inch lower, that there the air might be yet further expanded, than hitherto it 

 had been. And though this did at first seem to discompose our little beast, yet 

 after a while he grew very quiet, and continued so for a full quarter of an hour, 

 when being desirous to try what operation a further rarefaction of the air would 

 have upon him, we caused three exsuctions more to be made by the pump, be- 

 fore we discovered him to be in manifest danger, (at which time the bladder ap- 

 peared much fuller than before) but then we were obliged to let the air into the 

 outward receiver, whereupon the mouse was more speedily revived than one 

 would have suspected. 



And these trials of the power of assuefactlon seemed the more considerable, 

 because the air in which the mouse had all this while lived, had been clogged 

 and infected with the excrementitious effluviums of his body, for it was the 

 same all along, we having purposely forborn to take off the bladder, whose re- 

 gular intumescencies and shrinkings sufficiently manifested that the vessel, 

 whereof it was a part, did not leak. 



Postscript. Though the success of the recited experiments is y&ry promising, 

 yet a subsequent trial or two, whose particularities are slipt out of my memory, 

 oblige me in point of candour to declare, that, for further satisfaction, the trials 

 of the power of accustomance in reference to air unfit for respiration, ought to 

 be both reiterated, and to be made in different sorts of animals. 



The Fifteenth Title. 



Some Experiments, showing that Air, become unfit for Respiration, may retain its 



wonted Pressure. 



Exp. I. — We took a mouse of an ordinary size, and having (not without 

 some difficulty) conveyed him into an oval glass, fitted with a somewhat long 

 and considerably broad neck, which we had provided, that it might be wide 

 enough to admit a mouse in spight of his struggling ; we conveyed in after him 

 a mercurial gauge, in which we had diligently observed and marked the station 

 of the mercury, and which was so fastened to a wire reaching to the bottom of 



